From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4653F636.1090700@domain.hid> Date: Wed, 23 May 2007 10:07:18 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <528bc2040705222310j179c996w9f7732032038886b@domain.hid> <305035a40705230025q50e05401xa76dbb966a24c254@domain.hid> In-Reply-To: <305035a40705230025q50e05401xa76dbb966a24c254@domain.hid> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: jan.kiszka@domain.hid Subject: Re: [Xenomai-core] getting negative values in interrupt latency in xenomai List-Id: "Xenomai life and development \(bug reports, patches, discussions\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: manoj kumar , xenomai@xenomai.org Gregory CLEMENT wrote: > 2007/5/23, manoj kumar : >> Hi, >> >> i am runnigthe latency test on i386 platform with 1 GB ram and intel pentium >> 4 runnig at 2.66GHz . i am getting some negative values as lat best and avg. >> The results are as below >> >> >> User space interrupt latency output >> >> == Sampling period: 10000 us >> >> == Test mode: periodic user-mode task >> >> == All results in microseconds >> >> warming up... >> >> RTT| 00:00:01 (periodic user-mode task, 10000 us period, priority 99) >> >> RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat >> worst >> >> RTD| -1.775| -1.374| 0.953| 0| -1.775| >> 0.953 >> >> RTD| -1.790| -1.355| 3.142| 0| -1.790| >> 3.142 >> >> RTD| -1.812| -1.266| 4.158| 0| -1.812| >> 4.158 >> >> RTD| -1.797| -1.272| 6.602| 0| -1.812| >> 6.602 >> >> RTD| -1.764| -1.365| 0.575| 0| -1.812| >> 6.602 >> >> RTD| -1.895| -1.370| 0.859| 0| -1.895| >> 6.602 >> >> RTD| -1.857| -1.421| 0.908| 0| -1.895| >> 6.602 >> >> RTD| -1.782| -1.293| 5.845| 0| -1.895| >> 6.602 >> >> RTD| -1.929| -1.362| 1.204| 0| -1.929| >> 6.602 >> >> RTD| -1.775| -1.359| 0.844| 0| -1.929| >> 6.602 >> >> RTD| -1.794| -1.346| 0.724| 0| -1.929| >> 6.602 >> >> RTD| -1.756| -1.318| 1.021| 0| -1.929| >> 6.602 >> >> RTD| -1.775| -1.269| 8.064| 0| -1.929| >> 8.064 >> >> RTD| -1.805| -1.395| 0.893| 0| -1.929| >> 8.064 >> >> RTD| -1.779| 1.530| 281.147| 0| -1.929| >> 281.147 >> >> RTD| -1.959| -1.362| 1.118| 0| -1.959| >> 281.147 >> Could any figure out why these negative values are coming and reason behind >> that and how i can avoid these. >> >> is it a configuration issuse. > > You have to calibrate xenomai by feeding with your average latency > /proc/xenomai/latency > ...or by setting it at compile time in the kernel .config. Anyway, I would worry more about that +280 us latency. Probably SMI-related. Please check TROUBLESHOOTING regarding potential reasons and solutions. Jan